Amino acid racemization dating of quaternary deposits of central and Southern Italy

OrganicGeochemistry1987 Org. Geochem. Vol. 13, Nos 4-6, pp. 735-740, 1988 Printed in Great Britain.All rights reserved

0146-6380/88 $3.00+ 0.00 Copyright © 1988PergamonPress plc

Advances in

Amino acid racemization dating of Quaternary deposits of Central and Southern Italy GIORGIO BELLUOMINIand LAURETTADELITALA Centro di Studio per la Geochimica Applicata alla Stratigrafia Recente-q2NR c/o Dipartimento di Scienze della Terra, Universit~ "La Sapienza", Roma Abstract--Results are discussed of amino acid racemization dating of numerous samples of bones, teeth, tooth enamel and fossil shells. Racemization dating proved to be a very useful tool to date non-marine and marine deposits which are a few hundred thousand years old, as well as to correlate and chronologically classify even more ancient marine deposits. Aspartic acid racemization was used to date samples aged less than 80,000-100,000 yr; for more ancient samples, isoleucineepimerization, instead, was resorted to. In this work, dates were established for some important fragments of human bones and of large-mammalian fauna weighing a few grams, which would have been impossible to date with the ~4C technique, requiring a large amount of bone material. The extent of isoleucine epimerization was measured in Glycymeris genera to estimate the age of numerous marine deposits of the Tyrrhenian coast of Central-Southern Italy and of Sardinia. In the Tarquinia area (Latium) three marine terraces were identified, which were estimated to be approx. 120,000, 200,000 and 350,000yr old. In Sardinia, five marine horizons were identified; the youngest deposit (Neotyrrhenian) proved to be present at Punta Tramontana and Santa Reparata, while, at Riola and Stagno di Sassu, the most ancient marine deposits of Sardinia were found. In the Rome area, the Monte Mario Formation was estimated to be coeval with Monte delle Piche Formation. Finally, from the terraced coastal deposits of Capo Milazzo (Sicily), Panarea (Eolian archipelago), Archi (Calabria) and Gallipoli (Apulia), a Tyrrhenian age range of I00,000-120,000yr was obtained. Key words: Amino-acid geochronology, Quaternary deposits, racemization, epimerization

INTRODUCTION During the last 15 years, a new method of dating fossil samples using amino acid racemization has been developed (Bada, 1972, 1985; Schroeder and Bada, 1976). The method has an effective dating range beginning at a few thousand years b.p. and extending to several hundred thousand years (the Pleistocene and may eventually be useful in some cases throughout the Pliocene), the actual range being dependent upon the general temperature of the region where the sample was found. Only a few grams ( ~ 5) of fossil material are required for a racemization analysis. Therefore, this method offers the possibility of directly dating even the most precious and rare samples. Racemization dating is based on the fact that the molecules of amino acids in active living tissues are of the left-handed, or L-isomer, variety, that is the only form used by animal enzyme systems. When an animal dies or the tissue ceases to be metabolically active (e.g. tooth enamel), molecules begin to turn into the right-handed, or D-isomer, variety. The process continues until the ratio of the two isomers is 1 : 1. This reaction, known as racemization, occurs very slowly at well-known rates for each different amino acid. Since racemization is a chemical reaction, it is dependent on temperature. Thus, in order to date a fossil sample using this method, it is

necessary to evaluate the average temperature to which the fossil has been exposed. However, this temperature evaluation can be eliminated using a procedure in which the in situ rate of amino acid racemization for a particular area is calculated by measuring the extent of racemization in a sample dated by another method. After this "calibration" has been carried out, other samples from the general area can be dated, based on their extent of amino acid racemization. The amino acid racemization reaction has important applications in anthropology, paleontology and geochronology. This work shows the results of amino acid racemization dating of numerous fossil samples of bones, teeth, tooth enamel and shells derived from several sites of Central and Southern Italy.

EXPERIMENTAL

Fossil samples (about 5 g were used for analysis) are mechanically cleaned by removing residues of porous tissue and of soil attached to their surface or contained in their fissures; then they are carefully and repeatedly washed in 0.5 M HC1 using ultrasonication to remove the last traces of adhering foreign matter (Bada, 1985). After cleaning, the sample was hydrolyzed in double-distilled 6 M HCI for 735

736

GIORGIO BELLUOMIN1and LAURETTADELITALA

The accuracy of the ratio measurements is generally of the order of _+5% (BeUuomini and Bada, 1985).

24h and desalted by cation exchange chromatography. The ratios of alloisoleucine to isoleucine (ALLE/ILE), the ratios of the diastereomeric dipeptides L-leucyl-D-aspartic acid and L-leucyl-Laspartic acid (D/L) (Belluomini, 1981) were determined on an Automatic Amino Acid Analyzer, Carlo Erba Strumentazione, Mod. 3A28 M that is interfaced with a Spectra-Physics 4100 Computing integrator.

%~;T~

RESULTS Aspartic acid racemization was used to date samples aged less than 80,000-100,000 years (Bada, 1981). In particular (Fig. l and Table 1), dates were established of some important fragments of human

•

ARCHAEOLOGICAL AND PALAEONTOLOGICAL SITE~

•

MARINE DEPOSITS

s V,NCEN,O

PANTA LEO CASALS EL GIGLIO SANT AOOSTINO NUOVO SANT AGOSTINO VECCHIO LESTRA DELL OSPEOALE

.OTEL.'ATI

ORSO Cove •

Siena

..

CATIGNAN0

ai Castro

SAN PIETRO A MARE PUNTA TRAMONTANA

S

NTA REPARATA

--

A U R E L I A h ~ SAN COSI D RirDIC ICOLI Oe°, PONTE GALERIA DOP, MONTE MARZO PONTE OAL.ERIA MONTE DEL.L.;" PICHE

TAVOL.ARA

ROME~ • Latina

|

• ""

ISE RNIA - L.A PINF:TA DeDoeit

I

POZZO POZZO BORGO BORGO

STAGNO DXS A S S U

41

IS

ARENAS

CELA DEL TURCO

PLASMON BIANCHZ SABOTINO SANTA MARIA

'

TYRRHEANIAN

i

l

CALAMOSCA

EOLIAN

R, NORA

~

PANAREA

SEA

zs MZSAS-

Cove

NOTARCHIRtCO • Deposit CASTELCIVITA VENOSA Cove Lerno

Cove

PUNTA ROSSA CAVA DI SABEIA POZZO CEL.AN0

RO I LA

F~ o g g l O "~

PUNTALZ Caved

I

°,¢~,~ooo •

,o ~ '

M CAPOT;NDAR!

~"; T.~ SICILY

,

M~TERRANEAN~ s ~ SEA

MURSZA

I

ARc~

SPI NAGALLO Car*

I PanteLIerO i

.TE

Fig. 1. Locations of sites dated by the amino acid method.

GALLIPOLI

Dating of Quaternary deposits

737

Table 1. Aspartic acid racemization ages of human and animal fossil bones D/L aspartic acid

Aspartic acid b age (yr)

Bos taurus Bos taurus

0.150 0.154

K=~ = 2.7 x 10 -s y r - ' 3150

3010 + 50c

Catignano Village Bos taurus (Pescara) H u m a n rib

0.123 0.122

Ka,p = 9.6 x 10-6 yr - J 5500

5570 + 50~

0.103 0.107

Kas~ = 5.3 × 10-6yr -I 7000

6290 + 60c

0.119 0.120

K=,p = 4.8 x 10 -6 yr-1 10,600

10,420 + 150~

Site" Mursia Village (Pantelleria)

Orso Cave (Siena) Maritza Cave (L'Aquila)

Sample

Cervus elaphus H u m a n skull

Cervuselaphus H u m a n mandible

Collagen radiocarbon age (yr)

(Homo Maritza) Child rib

0.124

11,500

Uzzo Cave (Trapani)

Skeleton A Skeleton B

0.153 0.156

K~,v= 9.2 x 10-6yr -I

Paglicci Cave (Fnggia)

H u m a n rib (9)d Cervus elaphus (10) Cervus elaphus (18) Bos primigenius (21 c) Child rib (21d)

0.133 0.163 0.137 0.159 0.149

16,150 23,900 Kasp = 3.9 x 10 6yr-I 22,900 20,300

15,270 _+ 220 15,320 + 250 17,200 + 150c 24,210 + 410 24,720 + 4 2 0

Fossellone Cave (Latina)

Equus hidruntinus Cervus elaphus

0.289 0.330

K~,p= 8.9 x 10-6yr -I

25,380 -+ 1080c

Castelcivita Cave (Salerno)

Equus ¢aballus Cervus elaphus Cervus elaphus Elephascreutzburgi Megaceros cretensis Megaceroscretensis Megaceros cretensis

0.170 0.148 0.177 0.353 0.215 0.430 0.456

K=sp = 3.1 x 10-6yr -I 25,500 35,000 49,000 24,000 63,500 69,000

Simonelli Cave e (Crete) Bate Cave' (Crete)

10,420 _+ 60 9270 + 100c

9500

30,500 33,220 -+ 780c

°See Fig. 1 for site locations. bAges and K=,p constants were calculated from 1+

D/L

n i-2-~ Age

- 0.14

2 K=,p

where D/L is the aspartic acid enantiomeric ratio in the bone. The error on D/L ratios, experimentally measured

on known samples, is approx. 3%. Consequently there is a relative error of 10% on the data. CSample used for site calibration (Belluomini, 1981; Belluomini and Delitala, 1983). q n parentheses, stratigraphic sections. "The ages were calculated using K,,p of the Castelcivita cave for "calibration'", see Belluomini and Delitala (1983) for a discussion of how this K=sp value was calculated.

bones (Homo Maritza from the homonymous Cave, the child of the tomb found in the Paglicci Cave, etc.; Belluomini, 1981) and large-mammalian fauna (Elephas creutzburgi and Megaceros eretensis) from the Simonelli and Bate Caves of Crete which it was impossible to date with the radiometric J4C technique which requires a large amount of fossil material (Belluomini and Delitala, 1983). The isoleucine epimerization reaction was used instead to date samples collected from several nonmarine Pleistocene formations (Table 2). This reaction was chosen for dating the most ancient sites because it has one of the slowest racemization rates of the protein amino acids and it also tends to be less prone to contamination problems (Bada, 1985). To calibrate the isoleucine epimerization rate, use was made of teeth from the Isernia-La Pineta deposit, dated at approximately 0.70M.A. by K/Ar and Paleomagnetics (Coltorti et al., 1982). The isoleucine epimerization dates represents the first age determinations made directly on the fossil

material from the Italian deposits (Belluomini and Bada, 1985). In particular, ages were deposits (Belluomini and Bada, 1985). In particular, ages were estimated for Elephas falconeri from the Spinagallo Cave and Elephas mnaidriensis from the Puntali Cave (Fig. 1 and Table 2). The age value of the Elephas falconeri--the smallest representative of the Elephas family--appeared to be much older than the more robust dwarf form, Elephas mnaidriensis, which is not in line with modern theories on insular faunas, assigning an age older than the Elephasfalconeri to the latter. The age and correlation of shorelines of Central and Southern Italy were addressed by analyzing the extent of isoleucine epimerization in protein preserved in molluscan fossils collected from raised marine deposits. Amino acid geochronology can be used to provide relative ages of fossiliferous deposits or can be calibrated using other dating systems to provide absolute-age estimates. In the Montalto di Castro--Tarquinia area (Fig. 1

738

GIORGIO BELLUOMINI a n d LAURETTA DELITALA Table 2. Isoleucine epimerization ages of tooth enamel samples from pleistocene sites calculated using lsernia-La Pineta deposit for rate "calibration" Sample

ALLE/ILE h average

ALLE/ILE age (M.A.)"

Puntali Cave (Palermo--Sicily)

Elephas mnaidriensis

0.08

0.18

Spinagallo Cave (Siracusa--Sicily)

Elephas/alconeri

0.26

0.55

Capo Tindari Cave (Messina--Sicily)

Cervus siciliae

0.08

0.18

Aurelia Deposit (Rome)

Cereus elaphus

0.17

0.50'

San Cosimato Dep. (Romet

Dwerorhinus

0.22

0.66~

Redicicoli Dep. (Rome)

Equus

0.27

0.80'

Ponte Galeria Dep. (Rome)

Bos primigenius

0.28

0.84"

Notarchirico Dep. (Venosa--Basilicata)

Bos primigenius

0.16

0.5(I

lsernia--La Pineta Dep. (Molise)

Elephas antiquus

0.15

0.70a

Site~

"See Fig. 1 for site locations. ~The accuracy of the ALLE/ILE measurements is generally on the order of 5%. The calculated epimerization ages were estimated to have an uncertainty of + 25-30% (Belluomini and Bada, 1985). 'Calculated from In Q Age= ~ o

where

Q

t + ALLE/ILE 1 - 0 . 8 ALLE/ILE

and Kilo= 3.3 x 10 7yr t (Rome) K,~o= 3.1 × 10 7yr ~ (Venosa) K i ~ = 4 . 7 × 10 7yr k (Sicily) See Belluomini and Bada (1985) for a discussion of how this K,~o value was calculated. SAge determined by potassium-argon and paleomagnetic dating (Coltorti et al., 1982). This sample yields a "calibration" K~o value of 2.1 x 10 7 yr-~ (lsernia-La Pineta). 'Trom Belluomini et aL (1986b).

and Table 3), three marine terraces were identified, which were estimated to be approximately 120,000, 200,000 and 350,000 yr old. Such values are in good agreement both with those obtained for the same sediments with 23°Th/234U and ESR (electron spin resonance) techniques and with stratigraphic inter-

pretations of field observations made so far (Bartolini et al., 1984). Samples of Glycymeris fossils were collected from 11 coastal sites in Sardinia (Fig. 1) and grouped according to their respective amino acid ratios; five marine horizons were identified (Table 4). The

Table 3. Raised marine deposits in the Montalto Di Castro-Tarquinia area (Viterbo) Sitea

Elevation (m)

ALLE/ILE average

Casale S. Vincenzo

40

0.37 h

Podere S. Pietro

25

0.39

Bandita S. Pantaleo Casale I1 Giglio Sant'Agostino N uovo Sant'Agostino Vecchio

55 30 14 17

0.45~ 0.46 0.44 0.48

Lestra Dell'Ospedale

45

0.45b

Hotel Vulci Prati Di Santa Lucia

10 15

0.52 0.53~

ALLE/ILE

Age ( × 103 yr)" ESR

120

92 119 102 118

200

350

aSee Fig. I for site locations. bValu© obtained at Scripps Institution of Oceanography, La Jolla, California. CFrom Bartolini et aL (1984).

23°Th/234U 94~9;

105+6;

99 + 1 8 -6

101 + 6

115 + 1 5 -13

202-259

212 + 38

163--178

156 + 12

211 + 50

200 + 56 -20

Dating of Quaternary deposits

739

Table 4. Groupings of Sardinia marine deposits based on the similarity in ALLE/ILE ratio in Glycymeris genera Elevation (m) Sample

Sites Punta Tramontana Santa Reparata Nora Santa Reparata Tavolara Cala Fighera Cala D¢I Turco San Pietro A Mare Santa Reparata

ls Arenas Is Mesas-Calamosca Riola Stagno Di Sassu

3.25 3.90 1.60 3.60 1.50 1.80 0.50 2.20 1.50 1.50 3.10 0.50 0.30 1.40 1.20 1.30 3.60 2.80 6.80 - 4 - 14

PT3a PT2b SRE2 NR I SRCI TV1 CF1 CT1 SPM1 SPM2 SPM3 SREI SRDI SRla SR1 ISl IS2 IS3 CLI0 RL 1 SSS1

ALLE/ILE average

ALLE/ILE Age (yr)b

0.21 0.23 0.25 0.28 0.29 0.40 0.36 0.37 0.35 0.38 0.41 0.34 0.37 0.38 0.41 0.38 0.39 0.40 0.54 0.64 0.68

70,000 90,000 120,000

From 200,000 to 300,000 > 300,000

aSee Fig. 1. for site locations. ~From Belluomini et al. (1986a). N e o t y r r h e n i a n p r o v e d to be p r e s e n t at P u n t a Tramontana and Santa Reparata; The Eutyrrhenian a t T a v o l a r a , C a l a F i g h e r a , C a l a del T u r c o , S a n P i e t r o a M a r e , Is A r e n a s a n d S a n t a R e p a r a t a , while a n i n t e r m e d i a t e a g e level w a s f o u n d a t N o r a a n d S a n t a R e p a r a t a . T h e f o r m a t i o n o f Is M e s a s - - C a l a m o s c a , w h i c h is o f N e o t y r r h e n i a n o r i g i n , g a v e a s u r p r i s i n g a g e r a n g i n g f r o m 2 0 0 , 0 0 0 to 350,000 y r ( B e l l u o m i n i et al., 1986a).

I n t h e R o m e a r e a (Fig. 1 a n d T a b l e 5), t h e M o n t e M a r i o F o r m a t i o n w a s e s t i m a t e d to be c o e v a l w i t h t h e M o n t e delle P i c h e F o r m a t i o n . B o t h a p p e a r e d to be older than the Ponte Galeria Formation, which was c a l c u l a t e d to be o v e r 700,000 y r old. H o w e v e r , t h e s e t h r e e m a r i n e d e p o s i t s , a r e t o o o l d to be d a t e d w i t h t h i s m e t h o d ( M a s t e r s a n d B a d a , 1977; B e l l u o m i n i , 1985). F i n a l l y , f r o m t h e t e r r a c e d c o a s t a l d e p o s i t s (Fig. 1

Table 5. Quaternary marine deposits of central and Southern Italy Sites Monte Mario (Rome) Monte Delle Piche (Rome) Ponte Galeria (Rome) Capo Milazzo (Sicily) Panarea (Eolian archipelago) Archi

(Calabria) Gallipoli (Apulia) Borgo Santa Maria (Latina) Punta Rossa (Latina) Cava Di Sabbia (Latina) Pozzo Bianchi (Latina) Pozzo Plasmon (Latina) Pozzo Celano (Latina) Borgo Sabotino (Latina)

Elevation (m)

ALLE/ILE average

ALLE/ILE age (M.A.)

80

0.98

1.5--2.0¢'d

12

0.97

1.5-2.0~

25

0.73b

0.7-1.0c

55

0.3~

0.1

55

0.34

0. I

I I0

0.35 ~

0.I

4

0.30b

0.1

20

0.36

0.1

10

0.45

0.2

6

0.61

0.4--0.6c

-31

0.77

0.7-1.0c

-50

0.80

0.7--1.0c

-44

0.73

0.7-1.0¢

-21

0.85

0.7-1.0¢

°Sec Fig. 1 for site locations. Walue obtained at Scripps Institution of Oceanography, La Jolla, California. q'his age should be considered only a rough estimate because of kinetic complications that affect fossil shells with extensive racemization (Masters and Bada, 1977). '~rhese two formations arc the most ancient ones investigated in our laboratory.

740

GIORGIO BELLUOMINIand LAURETTADELITALA

and Table 5) of Capo Milazzo (Sicily), Panarea (Eolian archipelago), Archi (Calabria) and Gallipolli (Apulia) located in Italy's deep South, a Tyrrhenian age of 100,000-120,000 yr was obtained (Belluomini, 1985). CONCLUSIONS In the few years that have elapsed since the study of amino acid racemization in fossil materials began, we have seen a variety of applications to archaeology, paleoanthropology, geochronology and paleoclimatology. The method is presently less precise than the more conventional isotopic techniques, which is hardly surprising in view of the many environmental factors which can affect chemical reactions. However, racemization has found useful applications in several instances where conventional techniques could not be applied, either because samples were too old or the amount of fossil material was too small. Finally, amino acid dating is a very important method for estimating the ages of marine deposits a few hundred thousand years old. In this study, the ages demonstrate tectonic activity in the Mediterranean basin and suggest the need for reassessment of geomorphologic correlations.

REFERENCES

Bada J. L. (1972) The dating of fossil bones using the racemization of isoleucine. Earth Planet. Sci. Lett. 15, 223-231. Bada J. L. (1981) Racemization of amino acids in fossil bones and teeth from the Olduvai Gorge Region,

Tanzania, East Africa. Earth Planet. Sci. Lett. 55, 292-298. Bada J. L. (1985) Amino acid racemization dating of fossil bones. Ann. Rev. Earth Planet. Sci. 13, 241-268. Bartolini C., Bosi C., Belluomini G. and Delitala L. (1984) Isoleucine epimerization as a tool for dating Northern Latium raised beaches. Boll. Soc. Geol. It. 103, 485-490. Belluomini G. (1981) Direct Aspartic acid racemization dating of human bones from archaeological sites of Central Southern Italy. Archaeometry 23, 125-137. Belluomini G. (1985) Risultati e prospettive di un nuovo metodo di datazione basato sulla racemizzazione degli aminoacidi. Contributi del Centro Linceo Interdisciplinare di Scienze Matematiche e Loro Applicazioni. Giornata di Studio sul Tema : Ar cheometria 69, 135-171.

Belluomini G. and Delitala L. (1983) Datazione di resti ossei e denti del Pleistocene superiore e dell'Olocene dell'area mediterranea con il metodo della racemizzazione degli aminoacidi. Geogr. Fis. Dinam. Quat. 6, 21-30. Belluomini G. and Bada J. L. (1985) lsoleucine epimerization ages of the dwarf elephants of Sicily. Geology 13, 451-452. Belluomini G., Branca M., Delitala L., Pecorini G. and Spano C. (1986a) Isoleucine epimerization dating of Quaternary marine deposits in Sardinia, Italy. Z. Geomorph. N.F. 62, 109-117. BeUuomini G., Branca M., Delitala L., Malatesta A. and Zarlenga F. (1986b) Isoleucine epimerization ages of some Pleistocene sites near Rome. Human Evolution !, 209-213. Coltorti M., Cremaschi M, Delitala M. C., Esu D., Fornaseri M., McPherron A., Nicoletti M., Van Otterloo R., Perette C., Sala B., Schidt V. and Sevink J. (1982) Reversed magnetic polarity at an early lower palaeolithic site in Central Italy. Nature 300, 173 176. Masters P. M. and Bada J. L. (1977) Racemization of isoleucine in fossil molluscs from indian middens and interglacial terraces in Southerm California. Earth Planet. Sci. Lett. 37, 173 183. Schr6eder R. A. and Bada J. L. (1976) A review of the geochemical applications of the amino acid racemization reaction. Earth Sci. Rev. 12, 347-391.